Optoelectronic transmission system and method

ABSTRACT

An optoelectronic transmission system has a photoemitter semiconductor component and a photodetector semiconductor component. The photoemitter semiconductor component has a radiation source for converting a first electrical signal into a first electromagnetic radiation and a first polarization filter having a first polarization direction for filtering the first electromagnetic radiation. The photodetector semiconductor component has a second polarization filter having a second polarization direction for filtering a second electromagnetic radiation and a sensor element for converting a second electromagnetic radiation which has been polarized by the polarization filter into a second electrical signal. In this case, the first polarization direction of the first polarization filter is identical to the second polarization direction of the second polarization filter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Utility patent application claims priority to German PatentApplication No. DE 10 2009 009 316.8 filed on Feb. 17, 2009, which isincorporated herein by reference.

FIELD OF INVENTION

The present invention relates to a photodetector semiconductorcomponent, a photoemitter semiconductor component, an optoelectronictransmission system, and a method for transmitting an electrical signal.

BACKGROUND

In many applications, it is necessary for electric circuits to beelectrically isolated. Such electric circuits can be electricallyisolated from one another by optocouplers, for example. Optocouplers aresemiconductor components which perform an electrical-optical-electricalconversion of a signal. They have at least one radiation emitter and oneradiation receiver which are coupled via an optical transmission link.The transmission link can be the free space or a wave-guiding system,for example glass, plastic or an optical waveguide.

SUMMARY

In one embodiment, an optoelectronic transmission system comprises aphotoemitter semiconductor component, which has a radiation source forconverting a first electrical signal into a first electromagneticradiation, and a photodetector semiconductor component, which has asensor element for converting a second electromagnetic radiation into asecond electrical signal. The photoemitter semiconductor componentfurthermore has a first polarization filter having a first polarizationdirection, which filters the first electromagnetic radiation, and thephotodetector semiconductor component furthermore has a secondpolarization filter having a second polarization direction, whichfilters the second electromagnetic radiation before it impinges on thesensor element. The first polarization direction of the firstpolarization filter is identical to the second polarization direction ofthe second polarization filter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures:

FIG. 1 shows a schematic illustration of an embodiment of anoptoelectronic transmission system according to the invention;

FIG. 2 shows a schematic illustration of an embodiment of a crosssection of a photodiode for an optocoupler in which a plurality ofstrips is formed in a metallization plane;

FIG. 3 shows a schematic illustration of an embodiment of a crosssection of a photodiode for an optocoupler in which a plurality ofstrips is formed in a doped region;

FIG. 4 shows a schematic illustration of an embodiment of a crosssection of a phototransistor for an optocoupler in which a plurality ofstrips is formed in a metallization plane; and

FIG. 5 shows a flowchart of a method for transmitting an electricalsignal from a first circuit to a second circuit.

DETAILED DESCRIPTION

Exemplary embodiments are explained in greater detail below, withreference to the accompanying figures. However, the invention is notrestricted to the embodiments specifically described, but rather can bemodified and altered in a suitable manner. It lies within the scope ofthe invention to suitably combine individual features and featurecombinations of one embodiment with features and feature combinations ofanother embodiment in order to arrive at further embodiments accordingto the invention.

FIG. 1 shows a schematic illustration of an embodiment of anoptoelectronic transmission system according to the invention. On theemission side, the optoelectronic transmission system 100 comprises afirst photoemitter semiconductor component 102, a second photoemittersemiconductor component 104 and a third photoemitter semiconductorcomponent 106. On the receiver side, the optoelectronic transmissionsystem 100 comprises a first photodetector semiconductor component 108,a second photodetector semiconductor component 110 and a thirdphotodetector semiconductor component 112.

Each of the photoemitter semiconductor components 102, 104, 106respectively converts an electrical signal into an electromagneticradiation and emits the latter.

The electromagnetic radiation is received by the photodetectorsemiconductor components 108, 110, 112 and converted there by eachphotodetector semiconductor component 108, 110, 112 respectively into afurther electrical signal. Consequently, a parallel transmission ofthree electrical signals by means of polarized electromagnetic radiationtakes place in the optoelectronic transmission system 100.

Each of the photoemitter semiconductor components 102, 104, 106comprises a polarization filter, wherein the polarization directions ofthe polarization filters of the photoemitter semiconductor components102, 104, 106 differ from one another. The polarization filter has theeffect that only an electromagnetic radiation having a predeterminedpolarization direction is emitted by the photoemitter semiconductorcomponent. The predetermined polarization direction is predefined by thepolarization filter. The emitted electromagnetic radiation can bedistinguished, on account of its predetermined polarization direction,from an interference radiation which is superposed with theelectromagnetic radiation during a transmission and whose polarizationdirection does not correspond to the predetermined polarizationdirection. What is made possible as a result is that the emittedelectromagnetic radiation, after transmission, can again be securely andreliably converted back into an electrical signal, even if aninterference radiation occurs during transmission.

In FIG. 1, the different polarization directions are illustratedschematically by hatchings of the photoemitter semiconductor components102, 104, 106. As shown in FIG. 1, by way of example, the polarizationdirection of the first photoemitter semiconductor component 102 isrotated by 135° with respect to the horizontal axis, the polarizationdirection of the second photoemitter semiconductor component 104 isrotated by 45° with respect to the horizontal axis, and the polarizationdirection of the third photoemitter semiconductor component 106 isrotated by 90° with respect to the horizontal axis. However, othervalues of the rotation are also possible. By way of example, thepolarization direction of the first photoemitter semiconductor component102 is rotated by 0° with respect to the horizontal axis, thepolarization direction of the second photoemitter semiconductorcomponent 104 is rotated by 60° with respect to the horizontal axis, andthe polarization direction of the third photoemitter semiconductorcomponent 106 is rotated by 120° with respect to the horizontal axis.

An unambiguous assignment of the polarized electromagnetic radiation tothe photoemitter semiconductor components 102, 104, 106 is possible onaccount of the different polarization directions. Moreover, aninterference radiation whose polarization direction does not correspondto any of the polarization directions of the photoemitter semiconductorcomponents 102, 104, 106 can be distinguished.

Each of the photodetector semiconductor components 108, 110, 112likewise comprises a polarization filter, wherein the polarizationdirections of the polarization filters of the photodetectorsemiconductor components 108, 110, 112 differ from one another. Thepolarization filter has the effect that only an electromagneticradiation having a predetermined polarization direction reaches thesensor element and is converted into an electrical signal by the sensorelement. The predetermined polarization direction is predefined by thepolarization filter. An electromagnetic radiation whose polarizationdirection does not correspond to the predetermined polarizationdirection is filtered out by the polarization filter and does not passto the sensor element. An undesired interference radiation whosepolarization direction does not correspond to the predeterminedpolarization direction is thus prevented from reaching the sensorelement. Consequently, the conversion into the electrical signal is notimpaired by the interference radiation either. The electromagneticradiation received by the photodetector semiconductor component is thussecurely and reliably converted into the electrical signal.

As illustrated schematically by hatchings in FIG. 1, in this case thepolarization directions of the photodetector semiconductor components108, 110, 112 respectively correspond to a polarization direction of oneof the photoemitter semiconductor components 102, 104, 106. By way ofexample, the first photodetector semiconductor component 108 has thesame polarization direction as the first photoemitter semiconductorcomponent 102, the second photodetector semiconductor component 110 hasthe same polarization direction as the second photoemitter semiconductorcomponent 104, and the third photodetector semiconductor component 112has the same polarization direction as the third photoemittersemiconductor component 106.

A photoemitter semiconductor component forms together with aphotodetector semiconductor component a transmission channel for anelectrical signal, where the photoemitter semiconductor component andthe photodetector semiconductor component have the same polarizationdirection. By way of example, the first photoemitter semiconductorcomponent 102 and the first photodetector semiconductor component 108form a first transmission channel, the second photoemitter semiconductorcomponent 104 and the second photodetector semiconductor component 110form a second transmission channel, and the third photoemittersemiconductor component 106 and the third photodetector semiconductorcomponent 112 form a third transmission channel. The polarizationfilters of the photoemitter semiconductor components 102, 104, 106 andof the photodetector semiconductor components 108, 110, 112 bring aboutchannel separation and crosstalk between the transmission channels isprevented on account of the different polarization directions. Moreover,an interference radiation whose polarization direction differs from thepolarization directions of the transmission channels has no influence onthe transmission. Consequently, the optoelectronic transmission system100 enables reliable parallel transmission of electrical signals. Anidentical polarization direction of the first and second polarizationfilters has the effect that the first electromagnetic radiation emittedby the photoemitter semiconductor component can be received by thephotodetector semiconductor component and converted into the furtherelectrical signal. An interference radiation which occurs duringtransmission of the first electromagnetic radiation from thephotoemitter semiconductor component to the photodetector semiconductorcomponent and the polarization direction of which does not correspond tothe first or second polarization direction is filtered out by the secondpolarization filter. Consequently, the interference radiation does notreach the sensor element and has no influence on the conversion of thesecond electromagnetic radiation received by the photodetectorsemiconductor component into the second electrical signal.

As illustrated in FIG. 1, the photodetector semiconductor components108, 110, 112 can be arranged in a manner directly adjoining oneanother. By way of example, the photodetector semiconductor components108, 110, 112 are monolithically integrated. No structural measures suchas, for example, partitions or spatial separation between thephotodetector semiconductor components 108, 110, 112 are required toavoid crosstalk. A compact and space-saving arrangement of thephotodetector semiconductor components 108, 110, 112 within theoptoelectronic transmission system 100 is thus made possible.

The photoemitter semiconductor components 102, 104, 106 are arranged ina manner spaced apart from one another, for example, as shown in FIG. 1.Each photoemitter semiconductor component 102, 104, 106 is integratedinto a separate chip housing, for example, wherein the chip housings arearranged on a common carrier.

However, the photoemitter semiconductor components 102, 104, 106 canalso be arranged in a common chip housing in a manner directly adjoiningone another on a carrier. The photoemitter semiconductor components 102,104, 106 can also be monolithically integrated. Since no structuralmeasures for separating the photoemitter semiconductor components 102,104, 106 or the photodetector semiconductor components 108, 110, 112 arerequired, the dimensions and the form of the photoemitter semiconductorcomponents 102, 104, 106 and of the photodetector semiconductorcomponents 108, 110, 112 can be chosen as desired. The photoemittersemiconductor components 102, 104, 106 and the photodetectorsemiconductor components 108, 110, 112 can thus be simply adapted andintegrated into an existing design. As illustrated in FIG. 1, thephotoemitter semiconductor components 102, 104, 106 and thephotodetector semiconductor components 108, 110, 112 can have a squareform. However, rectangular forms or n-gonal forms having more or fewerthan four corners are also possible. In this case, the photoemittersemiconductor components 102, 104, 106 and the photodetectorsemiconductor components 108, 110, 112 do not all have to have the sameform.

The optoelectronic transmission system 100 illustrated in FIG. 1 is amultichannel optocoupler, for example, which transmits a plurality ofelectrical signals in parallel from an input circuit to an outputcircuit, wherein the input circuit is electrically decoupled from theoutput circuit. The multichannel optocoupler is integrated in a chiphousing, for example, wherein the photoemitter semiconductor components102, 104, 106 and the photodetector semiconductor components 108, 110,112 are arranged on a common carrier.

The optoelectronic transmission system is suitable for secure andreliable transmission of an electrical signal from a first circuit to asecond circuit. The electrical signal generated by the first circuit isconverted into an electromagnetic radiation having a predeterminedpolarization direction by the photoemitter semiconductor component. Thetransmission to the second circuit takes place by means of the polarizedelectromagnetic radiation. The photodetector semiconductor componentreceives the electromagnetic radiation and converts it into a furtherelectrical signal. The further electrical signal is provided to thesecond circuit and corresponds to the electrical signal generated by thefirst circuit. The photodetector semiconductor component is constructedin such a way that it only converts an electromagnetic radiation whosepolarization direction corresponds to the predetermined polarizationdirection. A radiation which is superposed with the polarizedelectromagnetic radiation during transmission and the polarizationdirection of which differs from the predetermined polarization directionis filtered out in the photodetector semiconductor component andtherefore does not reach the sensor element. Consequently, theoptoelectronic transmission system is robust with respect to aninterference radiation which occurs during transmission, and enablesreliable transmission of an electrical signal independently ofinterfering influences from the environment.

FIG. 2 shows a schematic illustration of an embodiment of a crosssection of a photodiode for an optocoupler in which a plurality ofstrips is formed in a metallization plane. The photodiode 200 is a PINphotodiode having a P-type layer 202, an N-type layer 204 and an I-typelayer 206 arranged between the P-type layer 202 and the N-type layer204. The P-type layer 202 is formed from a p⁺-doped region connected toan anode contact 208. The N-type layer 204 is formed from an n⁺-dopedregion connected to a cathode contact 210. The anode contact 208 and thecathode contact 210 contain aluminium or gold, for example. A coatinglayer 212, containing silicon nitride, for example, is arranged on theP-type layer 202.

A plurality of strips 214 is arranged in a metallization plane of thephotodiode 200. The plurality of strips 214 is formed above the P-typelayer 202, which forms an anode region of the photodiode 200. The strips214 are arranged for example in the same metallization plane as theanode contact 208 and contain for example the same material as the anodecontact 208. The metallization plane can be for example a wiring planeof a semiconductor component into which the photodiode 200 isintegrated. The strips 214 can be produced simply and cost-effectivelyin a standard semiconductor production process. No special processoptions or special structure sizes are required.

The plurality of strips 214 forms a polarization filter, wherein thestrips 214 are arranged parallel to one another in a plane, the width ofall the strips 214 is the same and the distance between all the strips214 is the same. An electromagnetic radiation (indicated by arrows inFIG. 2) is filtered by the polarization filter before it impinges on theanode region of the photodiode 200. As a result, only a radiation havinga specific polarization direction is converted into an electrical signalby the photodiode 200, which electrical signal can be tapped off at theanode contact 208 and at the cathode contact 210.

FIG. 3 shows a schematic illustration of an embodiment of a crosssection of a photodiode for an optocoupler in which a plurality ofstrips is formed in a doped region. In a manner similar to thephotodiode 200 from FIG. 2, the photodiode 300 is a PIN photodiodehaving a P-type layer 302, an N-type layer 304 and an I-type layer 306arranged between the P-type layer 302 and the N-type layer 304. TheP-type layer 302 is formed from a p⁺-doped region connected to an anodecontact 308. The N-type layer 304 is formed from an n⁺-doped regionconnected to a cathode contact 310. The anode contact 308 and thecathode contact 310 contain aluminium or gold, for example. A coatinglayer 312, containing silicon nitride, for example, is arranged on theP-type layer 302.

In the same way as in FIG. 2, the photodiode 300 comprises a pluralityof strips 314 forming a polarization filter. In contrast to FIG. 2, inFigure the plurality of strips 314 is formed by a structuring of thep⁺-doped region 302. The strips 314 are p⁺-doped partial regions whichrun parallel to one another. In one embodiment, the strips 314 areinterconnected within the P-type layer 302. Furthermore, the strips 314can also be connected to the anode contact 308 within the P-type layer302. In this case, the strips 314 simultaneously form a polarizationfilter and an anode region of the photodiode 300.

FIG. 4 shows a schematic illustration of an embodiment of a crosssection of a phototransistor for an optocoupler in which a plurality ofstrips is formed in a metallization plane. The phototransistor 400 is annpn transistor having a semiconductor substrate 402 of the n⁻ conductiontype connected to a collector contact 408. A p⁻-doped region 404 isintroduced into the semiconductor substrate 402, and is connected to abase contact 410. An n⁺-doped region 406 is introduced into the p⁻-dopedregion 404, and is connected to an emitter contact 412.

A plurality of strips 414 is arranged in a metallization plane of thephototransistor 400. The plurality of strips 414 is formed above thep⁻-doped region 404, which forms a base region of the phototransistor400. The strips 414 are arranged for example in the same metallizationplane as the base contact 410 and the emitter contact 412 and containfor example the same material as the base contact 410 and the emittercontact 412. The metallization plane can be for example a wiring planeof a semiconductor component into which the phototransistor 400 isintegrated. The strips 414 can thus be produced simply andcost-effectively in a standard semiconductor production process. Nospecial process options or special structure sizes are required.

The plurality of strips 414 forms a polarization filter, wherein thestrips 414 are arranged parallel to one another in a plane, the width ofall the strips 414 is the same and the distance between all the strips414 is the same. An electromagnetic radiation (indicated by arrows inFIG. 4) is filtered by the polarization filter before it impinges on thebase region of the phototransistor 400. As a result, only a radiationhaving a specific polarization direction is converted into an electricalsignal by the phototransistor 400, which electrical signal can be tappedoff at the collector contact 408 and at the emitter contact 412.

In one embodiment, the polarization filter of the phototransistorcomprises, in a manner similar to the photodiode 300 shown in FIG. 3, aplurality of strips which are arranged parallel to one another and whichare formed in the p⁻-doped base region of the phototransistor.

In one embodiment, the strips 214, 314, 414 which are arranged parallelto one another and are shown in FIG. 2, FIG. 3 and FIG. 4 are connectedto one another. By way of example, the strips 214, 314, 414 form ameandering form. As an alternative, a ring can be formed within themetallization plane or within the doped region 302 around the strips214, 314, 414, said ring being connected to the ends of the strips 214,314, 414 and thus providing for an interconnection of the strips 214,314, 414.

In the case of the embodiments illustrated in FIG. 2 and FIG. 4, theplurality of strips 214, 414 are arranged in a metallization plane. Inanother embodiment, the strips 214, 414 are formed in a polysiliconplane. In a further embodiment, the strips 214, 414 are formed in aplurality of planes, these planes comprising a metallization planeand/or a polysilicon plane. The strips run parallel to one another ineach plane and the strips of the different planes all extend in the samelongitudinal direction. The strips of the different planes can bearranged in a manner offset with respect to one another in thetransverse direction, such that the filter properties of thepolarization filter are determined by the distance between the strips ofthe different planes.

In a manner similar to the embodiments illustrated in FIG. 2, FIG. 3 andFIG. 4, a photothyristor which can be used in an optocoupler cancomprise a polarization filter. The polarization filter is formed in aregion of a gate of the photothyristor and comprises a plurality ofstrips arranged parallel to one another, which is arranged in a dopedregion, in a metallization plane and/or a polysilicon plane. Thephotothyristor converts an electromagnetic radiation having a specificpolarization direction into an electrical signal which can be tapped offat an anode contact and a cathode contact of the photothyristor.

A light-emitting diode for an optocoupler, which converts an electricalsignal into an electromagnetic radiation, can comprise a polarizationfilter constructed in a manner corresponding to one of the polarizationfilters illustrated in FIG. 2, FIG. 3 and FIG. 4. The polarizationfilter has the effect that the light-emitting diode emits anelectromagnetic radiation having a predetermined polarization direction.The light-emitting diode comprises gallium arsenide, for example, andemits in the infrared range.

The embodiments of a photodiode 200, 300, of a phototransistor 400 andof a photothyristor as described with reference to FIG. 2, FIG. 3 andFIG. 4 are examples of a photodetector semiconductor component which canbe used in an optocoupler. The embodiment of a light-emitting diode asdescribed with reference to FIG. 2, FIG. 3 and FIG. 4 is an example of aphotoemitter semiconductor component which can be used in anoptocoupler. The photodiode 200, 300, the phototransistor 400, thephotothyristor and the light-emitting diode can be used as photodetectorsemiconductor component 108, 110, 112 and as photoemitter semiconductorcomponent 102, 104, 106, respectively, in an optoelectronic transmissionsystem 100 illustrated in FIG. 1. The optoelectronic transmission systemis a multichannel optocoupler, for example, wherein each transmissionchannel has a different polarization direction. A photoemittersemiconductor component forms together with a photodetectorsemiconductor component a respective transmission channel, wherein apolarization filter of the photoemitter semiconductor component has thesame polarization direction as a polarization filter of thephotodetector semiconductor component.

In one embodiment, the photodetector semiconductor components 108, 110,112 and the photoemitter semiconductor components 102, 104, 106 areintegrated into a common chip housing. In an alternative embodiment, thephotodetector semiconductor components 108, 110, 112 are arranged inseparate chip housings, and the photoemitter semiconductor components102, 104, 106 are also arranged in separate chip housings. In this case,a different polarization direction can be achieved by the chip housingsof the photoemitter semiconductor components 102, 104, 106 beingarranged in a manner rotated with respect to one another. The chiphousings of the photodetector semiconductor components 108, 110, 112 arelikewise arranged in a manner rotated with respect to one another,wherein the rotation of one of the chip housings of the photodetectorsemiconductor components 108, 110, 112 respectively corresponds to therotation of one of the chip housings of the photoemitter semiconductorcomponents 102, 104, 106.

FIG. 5 shows a flowchart of a method 500 for transmitting an electricalsignal from a first circuit to a second circuit.

In 502, the electrical signal is converted into an electromagneticradiation.

In 504, the electromagnetic radiation is polarized in a predeterminedpolarization direction and emitted.

In 506, the polarized electromagnetic radiation is received. In thiscase, an electromagnetic radiation whose polarization direction does notcorrespond to the predetermined polarization direction is filtered out.

In 508, the polarized electromagnetic radiation is converted into afurther electrical signal. In this case, the further electrical signalcorresponds to the signal which was converted into the electromagneticradiation in 502.

The method 500 enables secure transmission of the electrical signal froma first circuit to a second circuit. An interference radiation which issuperposed with the polarized electromagnetic radiation duringtransmission and the polarization direction of which does not correspondto the predetermined polarization direction has no influence on thetransmission since this interference radiation is filtered out.

The method 500 can be used to transmit a plurality of electrical signalsin parallel, wherein each electrical signal is converted into anelectromagnetic radiation having a predetermined polarization direction.In this case, crosstalk can be avoided by virtue of a differentpolarization direction of the electromagnetic radiation being chosen foreach electrical signal.

In the method, the electrical signal is reliably transmitted from thefirst circuit to the second circuit by means of the electromagneticradiation. An interference radiation which is superposed with theelectromagnetic radiation and the polarization direction of whichdiffers from the predetermined polarization direction is filtered outand therefore has no influence on the transmission of the electricalsignal. Consequently, the method enables secure transmission of theelectrical signal in an environment in which interference occurs.

The devices of methods illustrated with reference to FIGS. 1-5 can beused to transmit information from one electrical potential of a firstcircuit to another electrical potential of a second circuit, while thetwo circuits are electrically isolated from one another. The informationcan comprise analogue or digital electrical signals. Such electricalisolation is employed for example in the field of power supply in thecase of switched-mode power supplies, in the field of data transmission,for example in the case of telecommunications or in the case of EDPapplications, in the field of control, for example in the case ofindustrial applications or in the automotive sector, or in the field ofESD protection circuits, for example for medical applications.

There are various configurations and developments of the embodiments:

In one configuration of the photodetector semiconductor component, thepolarization filter comprises a plurality of strips which are arrangedparallel to one another and at an identical distance from one another.In this case, the position or orientation of the strips defines thepolarization direction of the polarization filter. The plurality ofstrips can be arranged in a plane. By way of example, the plurality ofstrips is formed in a metallization plane on or above a semiconductorsubstrate of the photodetector semiconductor component. Themetallization plane is a wiring plane of the semiconductor component,for example. As an alternative, the plurality of strips are formed indoped regions of the semiconductor substrate. The plurality of stripscan thus be produced simply and cost-effectively in a standardsemiconductor production process. No special process steps are necessaryfor forming the plurality of strips.

In a further configuration of the photodetector semiconductor component,the sensor element is embodied as a photodiode and the plurality ofstrips is arranged in a region of an anode of the photodiode in such away that an electromagnetic radiation impinging on the anode is filteredby the plurality of strips. The polarization filter can be added to anexisting design of a photodiode by the plurality of strips beingarranged within the anode. In this case, the dimensions of thephotodiode do not have to be enlarged. The polarization filter can thusbe integrated into an existing design of a photodiode in a neutralmanner in respect of area.

In another configuration of the photodetector semiconductor component,the sensor element is embodied as a phototransistor and the plurality ofstrips is arranged in a region of a base of the phototransistor in sucha way that an electromagnetic radiation impinging on the base isfiltered by the plurality of strips. The polarization filter can beadded to an existing design of a phototransistor by the plurality ofstrips being arranged within the base. In this case, the dimensions ofthe phototransistor do not have to be enlarged. The polarization filtercan thus be integrated into an existing phototransistor in a neutralmanner in respect of area.

One development of the photodetector semiconductor component comprises afurther polarization filter and a further sensor element, wherein afirst polarization direction of the polarization filter differs from asecond polarization direction of the further polarization filter. Thisphotodetector semiconductor component is suitable for use in amultichannel optocoupler, wherein crosstalk between the channels isprevented by virtue of the polarization direction of the polarizationfilters being different and only electromagnetic radiation with aspecific polarization direction reaching the respective sensor element.

In one configuration of the photodetector semiconductor component, thesensor element and the further sensor element are arranged on a carrierin a manner directly adjoining one another. Crosstalk is avoided byvirtue of only an electromagnetic radiation with a predeterminedpolarization direction being fed to the respective sensor element,wherein the polarization direction of each sensor element is different.Consequently, no elements or structural measures which prevent crosstalkhave to be provided between the sensor elements, rather the sensorelement and the further sensor element can be arranged on a carrier in aspace-saving manner.

In one configuration of the photodetector semiconductor component, thesensor element, the polarization filter, the further sensor element andthe further polarization filter are arranged in a chip housing.

In one configuration of the photoemitter semiconductor component, theradiation source is embodied as a light-emitting diode. By way ofexample, the photoemitter semiconductor component comprises aninfrared-emitting diode having a high efficiency.

In one configuration of the photoemitter semiconductor component, thepolarization filter comprises a plurality of strips which are arrangedparallel to one another and at an identical distance from one another.The plurality of strips can be arranged in a plane. The position or theorientation of the strips in this case determines the polarizationdirection of the polarization filter.

One development of the photoemitter semiconductor component comprises afurther polarization filter and a further radiation source, wherein afirst polarization direction of the polarization filter differs from asecond polarization direction of the further polarization filter. Thisphotoemitter semiconductor component is suitable for use in amultichannel optocoupler, wherein crosstalk between the channels isprevented by virtue of the polarization direction of the polarizationfilters being different. On account of the different polarizationdirections, a radiation of the radiation source can be distinguishedfrom a radiation of the further radiation source.

In one configuration of the photoemitter semiconductor component, theradiation source, the polarization filter, the further radiation sourceand the further polarization filter are arranged in a chip housing.

One development of the optoelectronic transmission system comprises afurther photodetector semiconductor component and a further photoemittersemiconductor component, wherein a third polarization direction of thefurther photodetector semiconductor component is identical to a fourthpolarization direction of the further photoemitter semiconductorcomponent, and wherein the first and second polarization directionsdiffer from the third and fourth polarization directions. Theoptoelectronic transmission system thus comprises two transmissionchannels, wherein the photodetector semiconductor component and thephotoemitter semiconductor component form a first transmission channel,and wherein the further photodetector semiconductor component and thefurther photoemitter semiconductor component form a second transmissionchannel. The electromagnetic radiation of the two transmission channelshas a predetermined polarization direction, wherein the polarizationdirection of the first transmission channel differs from thepolarization direction of the second transmission channel. Since eachtransmission channel operates with its own polarization direction,crosstalk between transmission channels is prevented. Consequently, aplurality of electrical signals can be transmitted in parallel in asecure and reliable manner.

In one configuration, the optoelectronic transmission system is arrangedin a chip housing. In an alternative embodiment, the photodetectorsemiconductor component and the photoemitter semiconductor component arearranged in separate chip housings.

In one configuration, the optoelectronic transmission system is amultichannel optocoupler and a plurality of electrical signals aretransmitted in parallel from a first circuit to a second circuit,wherein the circuits are electrically isolated from one another.

The invention claimed is:
 1. An optoelectronic transmission systemcomprising: a photoemitter semiconductor component, which comprises aradiation source for converting a first electrical signal into a firstelectromagnetic radiation, and a first polarization filter having afirst polarization direction for filtering the first electromagneticradiation based on the first polarization direction of the firstpolarization filter; and a photodetector semiconductor component, whichcomprises a second polarization filter having a second polarizationdirection for filtering a second electromagnetic radiation based on thesecond polarization direction of the second polarization filter, and asensor element for converting a second electromagnetic radiation whichhas been polarized by the second polarization filter into a secondelectrical signal, wherein the first polarization direction and thesecond polarization direction are identical polarization directions. 2.The optoelectronic transmission system of claim 1, further comprising: afurther photodetector semiconductor component and a further photoemittersemiconductor component, wherein a third polarization direction of thefurther photodetector semiconductor component is identical to a fourthpolarization direction of the further photoemitter semiconductorcomponent, and wherein the first and second polarization directionsdiffer from the third and fourth polarization directions.
 3. Theoptoelectronic transmission system of claim 1, wherein theoptoelectronic transmission system is arranged in a chip housing.
 4. Theoptoelectronic transmission system of claim 1, wherein the photodetectorsemiconductor component and the photoemitter semiconductor component arearranged in separate chip housings.
 5. The optoelectronic transmissionsystem of claim 1, wherein the optoelectronic transmission system is amultichannel.
 6. The optoelectronic transmission system of claim 1,wherein the first polarization filter comprises a plurality of stripswhich are arranged parallel to one another and at an identical distancefrom one another.
 7. The optoelectronic transmission system of claim 6,wherein the plurality of strips is formed in a metallization plane ofthe photoemitter semiconductor component.
 8. The optoelectronictransmission system of claim 6, wherein the plurality of strips isformed in a doped region of the photoemitter semiconductor component. 9.The optoelectronic transmission system of claim 8, wherein the dopedregion of the photodetector semiconductor component is a p⁻-doped baseregion.
 10. The optoelectronic transmission system of claim 7, whereinthe metallization plane of the photodetector semiconductor component isformed in the same metallization plane as an anode contact associatedwith the photodetector semiconductor component.
 11. The optoelectronictransmission system of claim 7, wherein the metallization plane of thephotodetector semiconductor component is formed above a P-type layer ofthe photodetector semiconductor component.
 12. The optoelectronictransmission system of claim 1, wherein the second polarization filtercomprises a plurality of strips which are arranged parallel to oneanother and at an identical distance from one another.
 13. Theoptoelectronic transmission system of claim 12, wherein the plurality ofstrips is formed in a metallization plane of the photodetectorsemiconductor component.
 14. The optoelectronic transmission system ofclaim 13, wherein the doped region of the photoemitter semiconductorcomponent is a p⁺-doped base region.
 15. The optoelectronic transmissionsystem of claim 12, wherein the plurality of strips is formed in a dopedregion of the photodetector semiconductor component.